Added thirdparty: boost library

thirdparty/include/boost/graph/lookup_edge.hpp

@@ -0,0 +1,55 @@
+//=======================================================================
+// Copyright 2009 Trustees of Indiana University
+// Author: Jeremiah Willcock
+//
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+//=======================================================================
+
+#ifndef BOOST_GRAPH_LOOKUP_EDGE_HPP
+#define BOOST_GRAPH_LOOKUP_EDGE_HPP
+
+#include <utility>
+#include <boost/config.hpp>
+#include <boost/utility/enable_if.hpp>
+#include <boost/graph/graph_traits.hpp>
+
+// lookup_edge: a function that acts like edge() but falls back to out_edges()
+// and a search when edge() is not provided.
+
+namespace boost
+{
+
+template < typename Graph >
+std::pair< typename boost::graph_traits< Graph >::edge_descriptor, bool >
+lookup_edge(typename boost::graph_traits< Graph >::vertex_descriptor src,
+    typename boost::graph_traits< Graph >::vertex_descriptor tgt,
+    const Graph& g,
+    typename boost::enable_if< is_adjacency_matrix< Graph >, int >::type = 0)
+{
+    return edge(src, tgt, g);
+}
+
+template < typename Graph >
+std::pair< typename boost::graph_traits< Graph >::edge_descriptor, bool >
+lookup_edge(typename boost::graph_traits< Graph >::vertex_descriptor src,
+    typename boost::graph_traits< Graph >::vertex_descriptor tgt,
+    const Graph& g,
+    typename boost::disable_if< is_adjacency_matrix< Graph >, int >::type = 0)
+{
+    typedef typename boost::graph_traits< Graph >::out_edge_iterator it;
+    typedef typename boost::graph_traits< Graph >::edge_descriptor edesc;
+    std::pair< it, it > oe = out_edges(src, g);
+    for (; oe.first != oe.second; ++oe.first)
+    {
+        edesc e = *oe.first;
+        if (target(e, g) == tgt)
+            return std::make_pair(e, true);
+    }
+    return std::make_pair(edesc(), false);
+}
+
+}
+
+#endif // BOOST_GRAPH_LOOKUP_EDGE_HPP